Anosognosia in Alzheimer's disease: association with patient characteristics, psychiatric symptoms and cognitive deficits

Abstract

Anosognosia is one of the major problems in the treatment and care of Alzheimer's disease (AD) patients. The aim of the study was to determine the patient characteristics, psychiatric symptoms, and cognitive deficits associated with anosognosia, because these are currently poorly understood. Eighty-four patients who met the National Institute of Neurological and Communicative Disease and Stroke-Alzheimer's Disease and Related Disorders Association criteria for probable AD were examined for anosognosia based on the difference between questionnaire scores of the patient and their caregiver. The relationship of anosognosia with patient characteristics (age, age at onset, duration of illness, education, Mini-Mental State Examination (MMSE), Clinical Dementia Rating (CDR), Hyogo Activities of Daily Living Scale (HADLS)), psychiatric symptoms (Neuropsychiatric Inventory (NPI), Geriatric Depression Scale (GDS)), and cognitive function (Digit Span, Word Fluency Test, Trail Making Test, Stroop Test, Raven's Coloured Progressive Matrices Test) were studied. Anosognosia showed positive correlations with age, age at onset, duration of illness, CDR, HADLS, and NPI disinhibition, and negative correlations with MMSE and GDS. Regarding cognitive function, only Part III of the Stroop Test was a predictor of anosognosia. The severity of anosognosia increased with disease progression and with a later age at onset. Subjective complaints of depression requiring self-monitoring of mood tended to decrease and, in contrast, inhibition of socially unsuitable behavior became more difficult as anosognosia worsened. Regarding cognitive function, anosognosia appeared to be associated with response inhibition impairment. Both disinhibition, as a psychiatric symptom, and response inhibition impairment are known to be correlated with disturbance of orbitofrontal function, which therefore may be associated with anosognosia.